Ultracapacitors and the Difference between Power and Energy

Ultracapacitors High power density and medium energy density

Batteries have low power density but high energy density, meaning they have a lot of energy that gets discharged slowly. Traditional capacitors, have high power density but low energy density, meaning they have less energy but can be discharged more quickly. Ultracapacitors fall somewhere in the middle, with high power density and medium energy density.